The mechanism of the reaction of Ni^+ (~2D) with ethane in the gas-phase wasstudied by using density functional theory. Both the B3LYP and BLYP functionals with standardall-electron basis sets are used to give the det...The mechanism of the reaction of Ni^+ (~2D) with ethane in the gas-phase wasstudied by using density functional theory. Both the B3LYP and BLYP functionals with standardall-electron basis sets are used to give the detailed information of the potential energy surface(PES) of [Ni, C_2, H_6]^+. The mechanisms forming the products CH_4 and H_2 in the reaction of Ni^+with ethane are proposed. The reductive eliminations of CH_4 and H_2 are typicaladdition-elimination reactions. Each of the two reactions consists of two elementary steps; C―C orC―H bond activations to form inserted species followed by isomerizations to form product-likeintermediate. The rate determining steps for the elimination reactions of forming CH_4 and H_2 arethe isomerizations of the inserted species rather than C―C or C―H bond activations. Theelimination reaction of forming H_2 was found to be thermodynamically favored compared to that ofCH_4.展开更多
Dissociation of molecular hydrogen （H2） is extensively studied to understand the mechanism of hydrogenation reactions. In this study, H2 dissociation by Aul-doped closed-shell titanium oxide cluster anions AuTi3O7 a...Dissociation of molecular hydrogen （H2） is extensively studied to understand the mechanism of hydrogenation reactions. In this study, H2 dissociation by Aul-doped closed-shell titanium oxide cluster anions AuTi3O7 and AuTi3O8 has been identified by mass spectrometry and quantum chemistry calculations. The clusters were generated by laser ablation and mass- selected to react with H2 in art ion trap reactor. In the reaction of AuTi3O8 with H2, the ion pair Au＋-O22 rather than Au＋-O2 is the active site to promote H2 dissociation. This finding is in contrast with the previous result that the lattice oxygen is usually the reactive oxygen species in H2 dissociation. The higher reactivity of the peroxide species is further supported by frontier molecular orbital analysis. This study provides new insights into gold catalysis involving H2 activation and dissociation.展开更多
Modeling of biomolecular systems plays an essential role in understanding biological processes, such as ionic flow across channels, protein modification or interaction, and cell signaling. The continuum model describe...Modeling of biomolecular systems plays an essential role in understanding biological processes, such as ionic flow across channels, protein modification or interaction, and cell signaling. The continuum model described by the Poisson- Boltzmann （PB）/Poisson-Nernst-Planck （PNP） equations has made great contributions towards simulation of these pro- cesses. However, the model has shortcomings in its commonly used form and cannot capture （or cannot accurately capture） some important physical properties of the biological systems. Considerable efforts have been made to improve the con- tinuum model to account for discrete particle interactions and to make progress in numerical methods to provide accurate and efficient simulations. This review will summarize recent main improvements in continuum modeling for biomolecu- lar systems, with focus on the size-modified models, the coupling of the classical density functional theory and the PNP equations, the coupling of polar and nonpolar interactions, and numerical progress.展开更多
The adsorption of 1,1-diamino-2,2-dinitroethylene （FOX-7） molecule on the AI（I 11） surface was investigated by the generalized gradient approximation （GGA） of density functional theory （DFT）. The calculations ...The adsorption of 1,1-diamino-2,2-dinitroethylene （FOX-7） molecule on the AI（I 11） surface was investigated by the generalized gradient approximation （GGA） of density functional theory （DFT）. The calculations employ a supercell （4 × 4 × 2） slab model and three-dimensional periodic boundary conditions. The strong attractive forces between oxygen and aluminum atoms induce the N--O bond breaking of the FOX-7. Subsequently, the dissociated oxygen atoms and radical fragment of FOX-7 oxidize the AI surface. The largest adsorption energy is --940.5 kJ/mol. Most of charge transfer is 3.3 le from the A1 surface to the fragment of FOX-7 molecule. We also investi- gated the adsorption and decomposition mechanism of FOX-7 molecule on the AI（111） surface. The activation en- ergy for the dissociation steps of P2 configuration is as large as 428.8 kJ/mol, while activation energies of other configurations are much smaller, in range of 2.4 to 147.7 kJ/mol.展开更多
文摘The mechanism of the reaction of Ni^+ (~2D) with ethane in the gas-phase wasstudied by using density functional theory. Both the B3LYP and BLYP functionals with standardall-electron basis sets are used to give the detailed information of the potential energy surface(PES) of [Ni, C_2, H_6]^+. The mechanisms forming the products CH_4 and H_2 in the reaction of Ni^+with ethane are proposed. The reductive eliminations of CH_4 and H_2 are typicaladdition-elimination reactions. Each of the two reactions consists of two elementary steps; C―C orC―H bond activations to form inserted species followed by isomerizations to form product-likeintermediate. The rate determining steps for the elimination reactions of forming CH_4 and H_2 arethe isomerizations of the inserted species rather than C―C or C―H bond activations. Theelimination reaction of forming H_2 was found to be thermodynamically favored compared to that ofCH_4.
基金Supported by the National Instrumentation Program(Grant no.2012YQ140005)the National Natural Science Foundation of China(Grant no.61505125)the Nature Science Foundation of Beijing(Grant no.4144069)
基金supported by the National Natural Science Foundation of China(No.21573246,No.21773253,and No.21773254)the Beijing Natural Science Foundation(2172059)the Youth Innovation Promotion Association,Chinese Academy of Sciences(2016030)
文摘Dissociation of molecular hydrogen （H2） is extensively studied to understand the mechanism of hydrogenation reactions. In this study, H2 dissociation by Aul-doped closed-shell titanium oxide cluster anions AuTi3O7 and AuTi3O8 has been identified by mass spectrometry and quantum chemistry calculations. The clusters were generated by laser ablation and mass- selected to react with H2 in art ion trap reactor. In the reaction of AuTi3O8 with H2, the ion pair Au＋-O22 rather than Au＋-O2 is the active site to promote H2 dissociation. This finding is in contrast with the previous result that the lattice oxygen is usually the reactive oxygen species in H2 dissociation. The higher reactivity of the peroxide species is further supported by frontier molecular orbital analysis. This study provides new insights into gold catalysis involving H2 activation and dissociation.
基金supported by the National Natural Science Foundation of China(Grant No.91230106)the Chinese Academy of Sciences Program for Cross&Cooperative Team of the Science&Technology Innovation
文摘Modeling of biomolecular systems plays an essential role in understanding biological processes, such as ionic flow across channels, protein modification or interaction, and cell signaling. The continuum model described by the Poisson- Boltzmann （PB）/Poisson-Nernst-Planck （PNP） equations has made great contributions towards simulation of these pro- cesses. However, the model has shortcomings in its commonly used form and cannot capture （or cannot accurately capture） some important physical properties of the biological systems. Considerable efforts have been made to improve the con- tinuum model to account for discrete particle interactions and to make progress in numerical methods to provide accurate and efficient simulations. This review will summarize recent main improvements in continuum modeling for biomolecu- lar systems, with focus on the size-modified models, the coupling of the classical density functional theory and the PNP equations, the coupling of polar and nonpolar interactions, and numerical progress.
文摘The adsorption of 1,1-diamino-2,2-dinitroethylene （FOX-7） molecule on the AI（I 11） surface was investigated by the generalized gradient approximation （GGA） of density functional theory （DFT）. The calculations employ a supercell （4 × 4 × 2） slab model and three-dimensional periodic boundary conditions. The strong attractive forces between oxygen and aluminum atoms induce the N--O bond breaking of the FOX-7. Subsequently, the dissociated oxygen atoms and radical fragment of FOX-7 oxidize the AI surface. The largest adsorption energy is --940.5 kJ/mol. Most of charge transfer is 3.3 le from the A1 surface to the fragment of FOX-7 molecule. We also investi- gated the adsorption and decomposition mechanism of FOX-7 molecule on the AI（111） surface. The activation en- ergy for the dissociation steps of P2 configuration is as large as 428.8 kJ/mol, while activation energies of other configurations are much smaller, in range of 2.4 to 147.7 kJ/mol.
